“Some recognised the error and left the answer blank and some spent far too long trying to figure it out and consequently ran out of time when doing the bigger mark questions towards the end of the exam," he told the BBC.

The latest error affected an AS-level exam sat on May 24. AS-levels are normally sat in the first year of sixth-form and grades count towards students’ university applications.

As part of the question, students were asked about the profits of a fictitious chocolate company. But the company’s adjoining profile information failed to show what its profits actually were – making it impossible for students to answer.

The question was worth a maximum of three marks.

An AQA spokesman said: "We are very sorry about the error in the paper.

"However, we do have a robust process for ensuring that none of our students will be disadvantaged as a result our mistake.

"The examiners who will be marking the paper are aware of the problem and marks will be adjusted to ensure that all students get the right grade."

The latest mistake comes just days after it was disclosed that a maths AS-level paper, sat by 6,790 pupils, contained an impossible question. In that case, information needed to solve a mathematical equation was also missing.

The OCR exam board, which set the paper, promised to take the error into account when marking the exam, amid students' concerns that the mistake could affect their university places.